Dye-based ink

ABSTRACT

A dye-based ink includes a dye and a solvent. The dye-based ink has a high print quality on plain paper. The dye-based ink may have a print quality similar to pigment-based inks. This may be particularly relevant for black inks.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 11/071,479, filed Mar. 3, 2005, which is a continuation-in-partof U.S. patent application Ser. No. 10/400,131, filed Mar. 25, 2003, nowU.S. Pat. No. 7,052,537, which itself claims the benefit of U.S.Provisional Application Ser. No. 60/610,922, filed Sep. 17, 2004. Eachof these applications is incorporated by reference herein in itsentirety.

BACKGROUND

Ink jet printing is generally a non-impact method for producing imagesby the deposition of ink droplets in a pixel-by-pixel manner to animage-recording element in response to digital signals.

The inks used in the various ink jet printers can be classified aseither dye-based or pigment-based. A dye is a colorant, which isdissolved in the carrier medium. A pigment is a colorant that isinsoluble in the carrier medium, but tends to be dispersed/suspended inthe form of small particles, often stabilized against flocculation andsettling by the use of dispersing agents. Pigment-based inks aregenerally considered to be less stable than dye-based Inks. The carriermedium can be a liquid or a solid at room temperature in both cases.Commonly used carrier media include water, mixtures of water and organicco-solvents and high boiling organic solvents, such as hydrocarbons,esters, ketones, etc.

Plain paper is generally used to refer to paper that has not beenspecially coated or designed for specialty uses. Plain paper isgenerally composed of cellulose fibers and fillers. In many cases,fillers tend to be anistropic to the flow of ink and generally havelittle effect on wicking. However, when ink travels along and throughcellulose fibers, the flow tends to be directional, and if a dye isdeposited along the way, either through bonding at active sites orevaporation of the solvents, it is seen as wicking. Dye-based inks wherethe dye tends to penetrate into the paper and/or wick, tend to result inlow optical density and/or ragged edges.

Pigment-based inks tend not to have the same problems as dye-base inkswhen printed on plain paper. Pigment based inks have been formed whichcan create a high print quality (PQ) on plain paper. Due to the factthat pigment-based inks have been found to provide higher print qualitythan traditional dye-based inks, traditional wisdom has been that inksrequiring a high print quality (typically black inks) should bepigment-based inks. One such high print quality pigment-based ink issold by Hewlett Packard under the trade-name HP 56 black ink jet printcartridge for the Deskjet 5550, product # C6656AN.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a fluid deposition systemincluding a fluid supply media according to one exemplary embodiment;

FIG. 2 is a graph of optical density achieved by inks of variousformulations; and

FIG. 3 is a comparison of print quality of an exemplary dye-based inkaccording to the disclosure, a pigment-based ink having a high printquality, and a traditional dye-based ink.

DETAILED DESCRIPTION

According to many embodiments disclosed herein, a dye-based ink may beformed which exhibits a high print quality on plain paper. Further, manyof these embodiments provide inks having at least a similar printquality on plain paper as those pigment-based inks demonstrating highprint quality (i.e. the dye-based inks have a print quality that issubstantially the same as or better than the print quality of the highprint quality pigment-based inks).

Print quality generally refers to various properties of the inkincluding the thinness of the lines printable using the ink, the opticaldensity of the ink, and edge acuity/sharpness. Relative print qualitymay be determined by printing a common image using two or more differenttypes of inks and comparing the quality of the images. Print quality maybe judged with reference to a standard such as a laser printer image.

According to some embodiments, a dye-based ink is provided which has ahigh optical density on plain paper. According to some embodiments, thedye-based ink has an optical density of at least about 1.3. According tosome of these embodiments, the ink has an optical density of at least1.4 or at least about 1.45. According to some of these embodiments, theink has an optical density of at least about 1.5.

According to many embodiments, the dye-based ink comprises a solvent anda dye. The dye-based ink may also comprise surfactants, humectants,biocides, anti-kogation agents, buffers, and/or other additives.

Many dye-based inks include water as a solvent, and may also include acosolvent. Cosolvents used in dye-based inks tend to be organiccosolvents. According to some embodiments, the ink may comprise up toabout 20 wt. % cosolvent. According to some of these embodiments, theink may comprise up to about 16 wt. % cosolvent. According to someembodiments, the ink may comprise at least about 5 wt. % cosolvent.According to some of these embodiments, the ink may comprise at leastabout 8 wt. % cosolvent. According to one embodiment, the ink comprisesabout 10 wt. % to about 16 wt. % cosolvent.

The cosolvent used in the ink may be selected based on polarity, wherepolarity generally refers to the sum of the molecular propertiesresponsible for the interaction forces between cosolvent and solutemolecules. Polarity may be measured for a cosolvent based on itsE_(T)(30) value. For a more detailed description of this parameter, see“Solvents and Solvent effects in organic chemistry,” second edition byC. Reichardt. For reference, water generally has an E_(T)(30) value of63 kcal/mol and most diols and glycols tend to have E_(T)(30) values ofabout 50 to 55.

In some embodiments, a cosolvent may be selected such that it has anE_(T)(30) value of no more than about 45 kcal/mol. In some embodimentsof the ink, each of the cosolvents or molecules which may serve ascosolvents in the ink has an E_(T)(30) value of no more than about 45kcal/mol.

According to some embodiments, a cosolvent may be selected such that ithas an E_(T)(30) value of at least about 25 kcal/mol. According to someof these embodiments, a cosolvent may be selected such that it has anE_(T)(30) value of at least about 30 kcal/mol or at least about 35kcal/mol. In some embodiments, all of the cosolvent (which may includeone or more different types of cosolvent), or molecules which may serveas cosolvent, that is present in the ink would meet one or more of thepreviously listed E_(T)(30) value parameters. Specifically, everycosolvent present in the ink may have an E_(T)(30) value of at leastabout 25 kcal/mol. According to some of these embodiments, eachcosolvent present in the ink may be selected such that it has anE_(T)(30) value of at least about 30 kcal/mol or at least about 35kcal/mol.

Some exemplary cosolvents which may be used for a dye-based ink having ahigh print quality may include 2-pyrrolidinone,1-(2-hydroxyethyl)-2-pyrrolidinone, 3-pyridylcarbinol,4-pyridylcarbinol, 3-(3-pyridylamino)-propionitrile,4-(2-hydroxyethyl)-morpholine, 4-hydroxy-1-methyl-piperidine,1-(2-hydroxyethyl)-2-imidazolidinone, N-(2-hydroxyethyl)morpholine andcombinations thereof. These cosolvents are believed to have E_(T)(30)values in the ranges discussed above and may be present in amounts asdiscussed above.

U.S. patent application Ser. No. 10/400,131 titled SOLVENT SYSTEMS FORINK-JET INKS, filed on Mar. 25, 2003, relates to inks having improveddecap, recovery, and color attributes. The disclosure of thisapplication is hereby Incorporated by reference in its entirety to theextent that it is consistent with the present disclosure.

In addition to the cosolvent, the dye-based ink comprises a dye.According to some embodiments, the ink may comprise at least about 0.1wt. % dye. According to some of these embodiments, the ink may compriseat least about 1 wt. % or at least about 2 wt. % dye. According to someembodiments, the ink may comprise up to about 10 wt. % dye. According tosome of these embodiments, the ink may comprise up to about 6 wt. % dye.

According to some embodiments, the dye may comprise an anionic dye.According to some embodiments, the dye may comprise an azo-dye(including dis- and trisazo), phthalocyanine dye, and/or xanthene dye,and may be sulfonated, carboxylated, and/or metallized. Exemplary dyeswhich may be used include Direct Black 168, Projet Fast Black, and/orProjet Cyan 1, all available from Avecia; and/or Acid Red 52 availablefrom Warner Jenkins.

An ink according to some embodiments may comprise a black dye and may bea black ink. In other embodiments, the ink is a non-black ink.

According to some embodiments, the ink may comprise surfactants. In someembodiments, the surfactant may be anionic or non-ionic and may be ahigh HLB surfactant. Exemplary surfactants include polymeric alkoxylates(e.g. Solsperse 2000 from The Lubrizol Corporation), secondary alcoholethoxylates (e.g., Tergitol series available from Union Carbide Co.),fluoro surfactants (such as FC170C available from 3M), fatty acidethoxylate surfactants (e.g., Alkamul PSMO-20 available fromRhone-Poulenc), fatty amide ethoxylate surfactants (e.g., Aldamide L203available from Rhone-Poulenc), amine oxide surfactants, sulfonylsurfactants, and diphenyl sulfonate derivatives.

According to some embodiments, the ink may comprise up to about 1 wt. %surfactant. According to some of these embodiments, the ink may compriseup to about 0.5 wt. % or up to about 0.25 wt. % surfactant. According tosome embodiments, the ink may comprise up to about 1 wt. % high HLBsurfactant. According to some of these embodiments, the ink may compriseup to about 0.5 wt. % or up to about 0.25 wt. % high HLB surfactant. TheHLB (hydrophilic-lipophilic balance) value empirically quantifies thebalance between the hydrophilic and hydrophobic parts of a surfactantmolecule in terms of both size and strength. HLB values of nonionicsurfactants range from 1 to 40, with lower values indicating greatersolubility in oil and higher values indicating greater solubility inwater. While what constitutes a high HLB may vary by surfactant, asurfactant with a high HLB value would generally have a HLB value inwater of at least about 20.

According to some embodiments, the ink comprises at least about 0.01 wt.% surfactant. According to some of these embodiments, the ink comprisesat least about 0.05 wt. % or 0.3 wt. % surfactant.

According to some embodiments, the ink may comprise a humectant. If ahumectant is used, it may be selected so that it will have an E_(T)(30)value within the range discussed above for the cosolvent. Particularly,in some embodiments, a humectant may be selected such that it has anE_(T)(30) value of no more than about 45 kcal/mol. According to someembodiments, a humectant may be selected such that it has an E_(T)(30)value of at least about 25 kcal/mol. According to some of theseembodiments, a humectant may be selected such that it has an E_(T)(30)value of at least about 30 kcal/mol or at least about 35 kcal/mol.According to some embodiments, the cosolvent that is selected serves asa humectant.

According to some embodiments, the dye-based ink comprises up to about25 wt. % humectant. According to some of these embodiments, the inkcomprises up to about 15 wt. % or up to about 5 wt. % humectant.According to some embodiments, the dye-based ink does not comprise anyhumectant.

The ink may comprise biocide to suppress growth of microorganisms.According to some embodiments, the ink comprises up to about 5 wt. %biocide. According to some of these embodiments, the ink comprises up toabout 2 or up to about 1 wt. % biocide. According to some embodiments,the ink comprises at least about 0.1 wt. % biocide. According to some ofthe embodiments, the ink comprises at least about 0.2 wt. % or at leastabout 0.5 wt. % biocide. Exemplary biocides include Nuosept 95,available from Huls America (Piscataway, N.J.); Proxel GXL, availablefrom Zeneca (Wilmington, Del.); and glutaraldehyde, available from UnionCarbide Company (Bound Brook, N.J.) under the trade designation Ucarcide250.

The ink may comprise buffer/pH control agent to control the pH of theink. According to some embodiments, the ink comprises up to about 10 wt.% buffer or other pH control agent. According to some of theseembodiments, the ink comprises up to about 2 wt. % or up to about 1 wt.% buffer. According to some embodiments, the ink comprises at leastabout 0.1 wt. % buffer or other pH control agent. According to some ofthe embodiments, the ink comprises at least about 0.2 wt. % or at leastabout 0.5 wt. % buffer. Exemplary buffers include Trizma Base, availablefrom companies such as Aldrich Chemical (Milwaukee, Wis.),4-morpholineethanesulfonic acid (MES), and 4-morpholinepropanesulfonicacid (MOPS).

The ink may comprise an anti-kogation agent to reduce kogation of theink. According to some embodiments, the ink comprises up to about 5 wt.% anti-kogation agent. According to some of these embodiments, the inkcomprises up to about 2 wt. % or up to about 1 wt. % anti-kogationagent. According to some embodiments, the ink comprises at least about0.1 wt. % anti-kogation agent. According to some of the embodiments, theink comprises at least about 0.2 wt. % or at least about 0.5 wt. %anti-kogation agent.

The ink may comprise a metal chelator to bind transition metal cationsthat may be present in the ink. Exemplary metal chelators includeethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaaceticacid (DTPA), trans-1,2-diaminocyclohexanetetraacetic acid (CDTA),(ethylenedioxy) diethylenedinitrilotetraacetic acid (EGTA), or otherchelators that can bind transition metal cations.

According to some embodiments, the ink comprises no more than about 15wt. % performance enhancing additives (e.g. biocide, pH control agent,metal chelating agent, and anti-kogation agent). According to some ofthese embodiments, the ink comprises no more than about 5 wt. %performance enhancing additives. According to some of these embodiments,the ink comprises no more than about 2 wt. % performance enhancingadditives.

The dye-based inks described above may be configured for use inconjunction with a fluid deposition system that deposits the ink on amedium to form an image. In some embodiments, the dye-based inksdescribed above may be configured for use in an ink jet printer.

There are various methods which may be utilized to control thedeposition of ink droplets on the image-recording element to yield thedesired image. In one process, known as continuous ink jet printing, acontinuous stream of droplets is charged and deflected in an imagewisemanner onto the surface of the image-recording element, while unimageddroplets are caught and returned to an ink sump. In another process,known as drop-on-demand ink jet printing, individual ink droplets areprojected as needed onto the image-recording element to form the desiredimage. Common methods of controlling the projection of ink droplets indrop-on-demand printing include piezoelectric transducers and thermalbubble formation. Ink jet printers have found broad applications acrossmarkets ranging from industrial labeling to short run printing todesktop document and pictorial imaging.

FIG. 1 schematically illustrates fluid deposition system 10 configuredto deposit a fluid 12 upon a medium 14. Fluid 12 comprises a liquidmaterial such as ink which creates an image upon medium 14. In otherapplications, fluid 12 may include or carry non-imaging materials,wherein system 10 is utilized to precisely and accurately distribute,proportion and locate materials along medium 14.

Medium 14 comprises a structure upon which fluid 12 is to be deposited.Medium 14 may comprise a sheet or roll of a cellulose based or polymericbased material, structures which are more three dimensional in shape,textiles, wood, plastic, and/or some other medium upon which fluid 12can be deposited.

According to some embodiments, a fluid deposition system may beconfigured to deposit inks of more than one color. According to someembodiments, a black ink of the fluid deposition system is comprised ofone of a dye-based ink and a pigment-based ink, and a non-black ink(i.e. a colored ink such as red, blue, yellow, etc.) of the fluiddeposition system is comprised of the other of a dye-based ink and apigment-based ink. According to some of these embodiments, the black inkcomprises a dye-based ink and the non-black ink comprises apigment-based ink. Particularly, in some embodiments, the blackdye-based ink is formulated as discussed above.

The following examples are presented to illustrate the presentembodiments and to assist one of ordinary skill in making and using thesame. The examples are not intended in any way to limit the scope of theclaims.

Example 1

An ink comprises,

-   -   a) 8 wt. % of 1-(2-ethylhydroxy)-2-pyrrolidinone    -   b) 8 wt. % of 2-pyrrolidinone    -   c) up to 1 wt % of ink jet ink additives such as biocides,        buffers, and surfactants    -   d) 4 wt. % Direct Black 168    -   e) the balance water

Example 2

An ink comprises,

-   -   a) 8 wt. % of 1-(2-ethylhydroxy)-2-pyrrolidinone    -   b) 8 wt. % 3-pyridylcarbinol    -   c) up to 1 wt % of ink jet ink additives such as biocides,        buffers, and surfactants    -   d) 4 wt. % Direct Black 168    -   e) the balance water

Example 3

An ink comprises,

-   -   a) 8 wt. % of 1-(2-ethylhydroxy)-2-pyrrolidinone    -   b) 8 wt. % of N-(2-hydroxyethyl)morpholine    -   c) up to 1 wt. % of ink jet ink additives such as biocides,        buffers, and surfactants    -   d) 4 wt. % Direct Black 168    -   e) the balance water

Example 4

An ink comprises,

-   -   a) 8.0 wt. % 2-pyrrolidinone    -   b) 8.0 wt. % 1-(2-hydroxyethyl)-2-imidazolidinone    -   c) 0.1 wt % biocide    -   d) 0.2 wt. % buffer (which can be MES, Trizma, or MOPS)    -   e) 4.0 wt. % anionic black dye

Example 5

An ink comprises,

-   -   a) 8.0 wt. % 2-pyrrolidinone    -   b) 0.1 wt. % biocide    -   c) 0.2 wt. % buffer (which can be MES, Trizma, or MOPS)    -   d) 4.0 wt. % anionic black dye

Example 6

Referring to FIG. 2, a plurality of dye-based inks were printed on plainpaper and optical density was measured for each sample using HP plainpaper.

Ink Cosolvent Dye A 15 wt. % 3-(3-Me-pyridylamino)- 4 wt. % of DirectBlack 168 propionitrile B 15 wt. % Dantocol DHE 4 wt. % of Direct Black168 C 15 wt. % 3-Me-1,5-pentanediol 4 wt. % of Direct Black 168 D 15 wt.% Dowanol TPM 4 wt. % of Direct Black 168 E 15 wt. % Dowanol PnB 4 wt. %of Direct Black 168 F 15 wt. % 1,2-hexanediol 4 wt. % of Direct Black168 G 10 wt. % 1-(2-hydroxyethyl)- 4 wt. % of Direct Black 1682-pyrrolidinone 10 wt. % 2-pyrrolidinone H 7.5 wt. % 1-(2-hydroxyethyl)-4 wt. % of Direct Black 168 2-pyrrolidinone 7.5 wt. % 2-pyrrolidinone I6 wt. % 1-(2-hydroxyethyl)- 4 wt. % of Direct Black 168 2-pyrrolidinone6 wt. % 2-pyrrolidinone

As can be seen in FIG. 2, inks G, H, and I have optical densities of atleast 1.4. As can also been seen, the optical density of theformulations of inks G, H, and I decreased as the amount of cosolventincreased.

Example 7

Referring to FIG. 3, the print quality (PQ) of three inks were measured.Ink 1 is an ink formulation according to example 4. Ink 2 is anexemplary traditional dye-based ink (not formulated as discussed above),sold for use with the Epson 870 printer. Ink 3 is an exemplarypigment-based ink, sold for use with the 800 and 900 series HP Deskjet.

PQ scores were measured by comparison to known samples. The maximumscore of 10 is given to output from a Laser printer. Pigment-basedblacks, like those used in the HP800 and 900 series or the LexmarkZ22/23 printers, which are judged to have high print quality commonlyscore higher than 7. To show paper independence, print quality is scoredover a selection of “plain” papers. Inks 1, 2, and 3 were printed usingan ink jet printer.

PQ scores (y-axis) are shown for the three different inks over such aselection of papers (X-axis). The papers used in this example include HPBrightWhite 80 Gsm A4, Datacopy 80 Gsm A4, Rey Matt (Intercopy) 80 GsmA4, Stein Beis Recyconomic 80 Gsm A4, HP BrightWhite 24# A, HP Printing80 Gsm A4, HP Everyday Ink jet 80 Gsm A4, Conqueror Wove Brilliant 100Gsm A4, Hokuetsu Kin Mari 64 Gsm A4, Golden Star 80 Gsm A4, SFI PPC 70Gsm A4, HP Everyday Copy & Printing 21# A, Navigator Soporset Pre Print80 Gsm A4, Gilbert Bond, 25% cotton, 20# A, Classic Laid Imaging 20#, HPMultipurpose 20# A, Multicopy 80 Gsm A4, Great White 20# A, HP Printing22# A, Sunace 64 Gsm A4, Hansol PPC 85 Gsm A4, Kodak BrightWhite 20# A,Double A 80 Gsm A4, Microprint Multisystems 20# A, Hammermill Copy Plus20# A, Kym Copy/Copy Stat 80 Gsm A4, HP Office 80 Gsm A4, PaperOne AllPurpose—Blue 80 Gsm A4, and Flagship 70 Gsm A4.

As can be seen in FIG. 3, Ink 1 (the dye-based ink as described in thisapplication) has about the same print quality as Ink 3 (a pigment-basedink), while Ink 2 (a traditional dye-based ink) does not have at leastabout the same print quality as Ink 3. Rather, Ink 2 has a significantlylower print quality than Ink 3.

Based on observations of inks formulated according to various examplesaccording to the present disclosure, results similar to those of Ink 1should be achievable using various black dyes in combination with any ofthe specific cosolvents listed above.

Illustrative Embodiments

A number of illustrative embodiments of the dye-based inks, andapplications incorporating such inks are discussed herein. Theembodiments described are intended to provide illustrative examples ofthe present additives and uses are not intended to limit the scope ofthe claimed subject matter.

One embodiment is directed to a dye-based ink. The ink comprises a dyeand a solvent. The dye-based ink has a high print quality on plainpaper.

Another embodiment is directed to a dye-based ink. The ink comprises adye and a cosolvent. All cosolvent in the ink consists essentially ofcosolvent having an E_(T)(30) value of about 25 kcal/mol to about 45kcal/mol.

An additional embodiment is directed to a dye-based ink. The inkcomprises a dye and a cosolvent. The cosolvent in the ink consistsessentially of cosolvent selected from a group consisting of2-pyrrolidinone, 1-(2-hydroxyethyl)-2-pyrrolidinone, 3-pyridylcarbinol,4-pyridylcarbinol, 3-(3-pyridylamino)-propionitrile,4-(2-hydroxylethyl)-morpholine, 4-hydroxy-1-methyl-piperidine, andcombinations thereof.

Another embodiment is directed to a dye-based ink. The ink comprisesabout 0.1 wt. % to about 10 wt. % dye, about 6 wt. % to about 20 wt. %cosolvent, up to about 0.5 wt. % high HLB surfactant, and up to about 15wt. % additives selected from a group consisting of biocides, pH controlagents, anti-kogation agents, and combinations thereof. All cosolvent inthe ink consists essentially of cosolvent having an E_(T)(30) value ofabout 25 kcal/mol to about 45 kcal/mol.

Another embodiment is directed to a dye-based ink. The ink comprises adye and a solvent. The ink has an optical density of at least about 1.45on plain paper.

Another embodiment is directed to a dye-based ink. The ink comprises adye and a solvent. The dye-based ink has an edge acuity and opticaldensity at least about the same as a pigment-based ink having a highprint quality.

An additional embodiment is directed to a method for forming an imageusing a fluid deposition system. The method comprises depositing adye-based ink on a medium, the dye-based ink being a black ink, anddepositing a pigment-based ink on a medium, the pigment-based ink beinga non-black ink. The dye-based ink has a high print quality on plainpaper and has a print quality on plain paper at least similar to thepigment-based ink.

Another embodiment is directed to a fluid supply. The fluid supplycomprises a reservoir, the reservoir containing a dye-based ink. Thedye-based ink may be formulated according to any of the above listedillustrative embodiments.

Another embodiment is directed to a fluid deposition system. The systemcomprises a fluid-dispensing device configured to dispense fluid upon amedium; and a fluid supply including a reservoir. The reservoircomprises an interior in fluid communication with a fluid-dispensingdevice, the reservoir containing a dye-based ink. The dye-based ink maybe formulated according to any of the above listed illustrativeembodiments.

Another embodiment is directed to a composition. The compositioncomprises a media having an image printed on the media. The image isformed by a black dye and has a high print quality. Print quality may bejudged by comparison to a similar image printed on a similar media usinga pigment from a pigment-based ink known to have a high print quality onplain paper. The media may be plain paper.

For each of the above listed inks, the ink may be a black ink or may bea non-black ink. For each of the fluid supplies discussed above, thefluid supply may be configured for use with an ink jet printer. For eachof the fluid deposition systems discussed above, the fluid depositionsystem may comprise an ink jet printer.

The invention has been described with reference to various specific andillustrative embodiments and techniques. However, it should beunderstood that many variations and modifications may be made whileremaining within the spirit and scope of the invention. For instance,the listed dyes and cosolvents are exemplary only and do not representan exhaustive list. Further, while the examples only show the use of asingle dye in a given ink, an ink may be composed of more than one dye.

1. A dye-based ink, comprising: a dye; and from about 5 wt. % to about20 wt. % cosolvents, the cosolvents including: 2-pyrrolidinone; and oneof: 1-(2-hydroxyethyl)-2-pyrrolidinone, or1-(2-hydroxyethyl)-2-imidazolidinone.
 2. The dye-based ink according toclaim 1 wherein the dye-based ink includes from about 0.1 wt. % to about10 wt. % dye, and wherein the dye-based ink further comprises: up toabout 0.5 wt. % high HLB surfactant; and up to about 15 wt. % additivesselected from a group consisting of biocides, pH control agents,anti-kogation agents, and combinations thereof; wherein the ink isconfigured to have an optical density of at least about 1.4 on plainpaper.
 3. The dye-based ink according to claim 1 wherein the cosolventshave an E_(T)(30) value from about 35 kcal/mol to about 45 kcal/mol. 4.The dye-based ink according to claim 2 wherein the cosolvents have anE_(T)(30) value from about 35 kcal/mol to about 45 kcal/mol.
 5. Thedye-based ink according to claim 1 wherein the ink is a black ink. 6.The dye-based ink according to claim 1 wherein the dye is anionic. 7.The dye-based ink according to claim 1, further comprising a humectanthaving an E_(T)(30) value from about 30 kcal/mol to about 45 kcal/mol.8. The dye-based ink according to claim 1 wherein the ink includes fromabout 10 wt. % to about 16 wt. % cosolvents.
 9. A fluid supply systemincluding the dye-based ink according to claim 1, the fluid supplysystem comprising a reservoir, the reservoir containing the dye-basedink.
 10. The fluid supply system according to claim 9 wherein thedye-based ink includes from about 0.1 wt. % to about 10 wt. % dye, andwherein the dye-based ink further comprises: up to about 0.5 wt. % highHLB surfactant; and up to about 15 wt. % additives selected from a groupconsisting of biocides, pH control agents, anti-kogation agents, andcombinations thereof; wherein the ink is configured to have an opticaldensity of at least about 1.4 on plain paper.
 11. A method for formingan image using a fluid deposition system, comprising: depositing adye-based ink on a medium, the dye-based ink being a black ink; anddepositing a pigment-based ink on the medium, the pigment-based inkbeing a non-black ink; wherein the dye-based ink has a print quality ofat least 1.4 on plain paper, and has a print quality on plain paperabout the same as the pigment-based ink.
 12. The method according toclaim 11 wherein the dye-based ink comprises: a dye; and from about 5wt. % to about 20 wt. % cosolvents, the cosolvents including:2-pyrrolidinone; and one of: 1-(2-hydroxyethyl)-2-pyrrolidinone, or1-(2-hydroxyethyl)-2-imidazolidinone.
 13. The method according to claim12 wherein the dye-based ink includes from about 0.1 wt. % to about 10wt. % dye, and wherein the dye-based ink further comprises: up to about0.5 wt. % high HLB surfactant; and up to about 15 wt. % additivesselected from a group consisting of biocides, pH control agents,anti-kogation agents, and combinations thereof.
 14. The method accordingto claim 12, further comprising a humectant having an E_(T)(30) valuefrom about 30 kcal/mol to about 45 kcal/mol.
 15. The method according toclaim 12 wherein the cosolvents have an E_(T)(30) value from about 35kcal/mol to about 45 kcal/mol.